feat: 018 — larger pig hitbox

[archae0pteryx]

Summary

• Adds HITBOX_PADDING = 16 constant (exported)
• Extracts buildHitRects(pigs, dpr) as pure function — rect size is PIG_SIZE + HITBOX_PADDING, centred on sprite with -(HITBOX_PADDING/2) offset
• syncRects delegates to buildHitRects; no Rust changes needed

Test plan

• 6 new unit tests covering padding size, x/y centering, dpr scaling, and multi-pig output
• task check green
• Clicking ~8px outside pig sprite still registers as pig click at runtime

Closes #16

Summary by CodeRabbit

• Improvements

  • Expanded and centered interaction areas around on-screen pigs so they are easier and more reliable to click or tap across display scales and device pixel ratios.

• Tests

  • Added automated tests validating hitbox padding, scaling, centering, and that one interaction rect is produced per pig to ensure consistent behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 6563b48 and e8ff469.

📒 Files selected for processing (1)

• src/hooks/usePigMovement.ts

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📝 Walkthrough

Walkthrough

Adds HITBOX_PADDING = 16, exports PigHitRect and buildHitRects(pigs, dpr) to produce centered, padded, DPR-scaled hit rectangles, and updates syncRects to use the helper. Adds tests verifying the constant, rect geometry, DPR scaling, and one-rect-per-pig behavior.

Changes

Hitbox Padding & Rect Building

Layer / File(s)	Summary
Constants src/hooks/usePigMovement.ts	Introduces export const HITBOX_PADDING = 16.
Types & Helper src/hooks/usePigMovement.ts	Adds export interface PigHitRect { x: number; y: number; size: number } and export function buildHitRects(pigs: PigState[], dpr: number): PigHitRect[] that produces centered padded squares sized (PIG_SIZE + HITBOX_PADDING) * dpr.
Integration src/hooks/usePigMovement.ts	syncRects now uses buildHitRects(pigs, dpr) for non-detailOpen rects; detailOpen full-viewport rect remains unchanged.
Tests / Verification src/hooks/usePigMovement.test.ts	New Vitest suite asserts HITBOX_PADDING === 16, verifies buildHitRects sizing, centering offset of HITBOX_PADDING/2, DPR scaling, and that output length equals input pigs.

sequenceDiagram
  participant User
  participant React_UI as React (PigSprite)
  participant Hook as usePigMovement
  participant Rust as WASM/Rust PigHitTester

  User->>React_UI: click near pig
  React_UI->>Hook: (render / polling) request pig rects
  Hook->>Hook: buildHitRects(pigs, dpr) -> padded DPR-scaled rects
  Hook->>Rust: update_pig_rects(rects)
  Rust->>Rust: PigHitTester.is_hit checks rects against cursor
  Rust-->>React_UI: (hit result) toggle click-through / state
  React_UI-->>User: UI response (detail open / click)

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 Sixteen pixels soft and round,

The pig's new footprint found its ground.
Clicks that missed now find their mark,
Little pigs glow in the park. 🥕

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: 018 — larger pig hitbox' clearly and concisely describes the main change: adding a larger hitbox to pig collision detection.
Linked Issues check	✅ Passed	The PR successfully implements all coding requirements from issue #16: HITBOX_PADDING constant exported, buildHitRects function computes correctly centered and padded hit rectangles, syncRects delegates to buildHitRects, and comprehensive unit tests verify the implementation.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to issue #16 requirements: new exports (HITBOX_PADDING, PigHitRect, buildHitRects), hitbox computation logic, and corresponding test coverage. No unrelated modifications detected.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/018-pig-hitbox

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/hooks/usePigMovement.ts`:
- Around line 127-130: The function buildHitRects currently returns an inline
object type; define and export a named type/interface (e.g., export type HitRect
= { x: number; y: number; size: number }) at the top of the module and change
the function signature to return HitRect[] (keeping PigState and dpr as-is),
then update any usages to reference HitRect so the module boundary uses a named
type.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 10d35d8c-05a9-4a3f-8cb9-ac5dacd734d5

📥 Commits

Reviewing files that changed from the base of the PR and between 9d896cf and 6563b48.

📒 Files selected for processing (2)

• src/hooks/usePigMovement.test.ts
• src/hooks/usePigMovement.ts